Several kinds of stink bugs feed in peach orchards, but they are not
pests in every orchard every year. Outbreaks appear to be cyclical.

The different species of stink bugs all
have similar life histories. They overwinter as adults under leaves and trash,
in the crowns of plants, and in clumps of grass on the orchard floor. They also
may be found outside the orchard in the crowns of plants such as blackberry or
in other protected places such as box piles and buildings. After mating, if
suitable host plants are not present in the orchard, adults move out of the
orchard to suitable host plants. Most of the species remain on weeds and ground
cover plants at this time, but the green stink bug may
move into the trees.

Adults have shield-shaped bodies that are about 0.5 inch long and
either brown or green with red, pink, or yellow markings. Barrel-shaped eggs are laid in clusters of about 14 on leaves
of broadleaf plants. Eggs are pearly white when first laid, later turning cream
colored or pinkish just before hatching. For consperse stink
bugs, a row of spines encircle the top of the eggs; the other species
have concentric black rings on top of the eggs. Early
nymphal stages have
various markings and patterns and no wings but resemble adults in shape. Nymphs
develop prominent wing pads in the fourth and fifth instars.

In early June, adults may migrate to trees where they deposit
eggs on the foliage. Adults from this generation also feed on developing fruit.
Second generation adults begin appearing in late July-August and can cause
severe damage to unharvested fruit. Second generation adults feed until the
onset of cool weather when they migrate back to protected sites or overwintering
hosts.

The rough shield bug, Brochymena sulcata, is a beneficial
insect and should not be confused with harmful stink bug species. This stink bug is common in Central Valley orchards; adults are
0.5 to 0.66 inches long, brownish or gray, with a very rough and angular shape.
Both nymphs and adults feed on caterpillars and other insects.

Stink bugs insert their needlelike mouthparts into fruit and feed on
plant juices. Initially the feeding sites are small, translucent, blue-green
spots. Damaged flesh under the skin later turns into gray or
whitish pithy areas. Gum may exude from feeding areas on green peaches. Because
frost damage can also cause the peach to exude gum, examine the peach flesh for
needlelike stains caused by stink bug feeding. Damaged areas will fail to grow,
and fruit attacked early in the season develops irregular, depressed areas or dimples. On nearly ripe fruit, exterior symptoms
resemble a bruise and if the fruit is peeled, white corky or pithy areas will
be found. One bug may feed on many fruit, thus a rather low population can
cause severe damage. On peaches, the damage resembles that caused by peach
rust; look for the presence of stink bugs to confirm
the cause of the damage.

Focus your stink bug management program
on keeping damaging populations from moving into the fruit trees. Monitor the
orchard ground cover in spring to detect the presence of
stink bugs.

Monitoring
and Treatment Decisions
Using a sweep net, begin monitoring after the weather has warmed up in
March and look for overwintering bugs feeding on curly dock, common
mullein, Russian
thistle (especially the base of the plant), or
other broad-leaved plants. If bugs are found, apply spot treatments to kill
adults before they can move to other locations. Orchards with legume cover
crops are likely to harbor stink bug populations. If stink bugs are present, cultivate or mow closely before
green fruit are present.

Monitor fruit beginning in early June every other week. Adult
bugs often hide on the opposite side of the limb as they are approached, making
them difficult to see. Look for sappy exudate on fruit, blue-green spots, or
gum that may exude from feeding sites. Some fruit should also be peeled to
detect the presence of white pithy or corky areas, or the trees can be sampled
with a beating tray.

Double cone traps that are baited with an aggregation
pheromone are also available for monitoring the consperse stink bug but will
not attract other species of stink bugs. Place these traps in tree crotches
near the orchard's border to detect the presence of adult consperse stink bugs.

Consider treating if damaged fruit is common or if adult bugs are
seen. Apply a full coverage spray to trees in affected areas of the orchard.
Clean cultivation of orchards in fall will discourage overwintering bugs.

Examine fruit on trees every week after color break (see PREHARVEST FRUIT SAMPLES) to
detect any developing problems in the orchard, and take a fruit damage sample
at harvest to assess the effectiveness of the current year's IPM program and to
determine the needs of next year's program (see FRUIT EVALUATION AT
HARVEST). Record results for the harvest(PDF) sample.

COMMENTS: Also controls katydids and Oriental fruit moth. Do not apply in more than 200 gal/acre.

B.

FORMETANATE HYDROCHLORIDE

(Carzol 92SP)

1 lb

0.25 lb

5 days

see comments

MODE OF ACTION GROUP NUMBER1: 1A

COMMENTS: Do not apply after petal fall.

C.

CARBARYL*

(Sevin XLR Plus)

3–4 qt

0.75–1 qt

12

1

MODE OF ACTION GROUP NUMBER1: 1A

COMMENTS: May cause increased spider mite
problems; best used late in the season. Do not apply more than 14 qt/acre/season.

D.

ENDOSULFAN*

(Thionex) 50WP

3–4 lb

1 lb

4 days

30

MODE OF ACTION GROUP NUMBER1: 2A

COMMENTS: Do not exceed 2
applications/season. This material cannot be used in areas where runoff may
contaminate riparian areas; only recommended for areas such as the southern San Joaquin Valley where runoff is not a problem.

E.

ESFENVALERATE*

(Asana XL)

4.8–14.5 fl oz

2–5.8 fl oz

12

14

MODE OF ACTION GROUP NUMBER1: 3

COMMENTS: Based on research in California
pistachio orchards, this material effectively controls stink
bugs. For dilute applications, do not apply in more than 200 gal water/acre at the 5.8 oz rate.

**

For dilute applications, rate is per 100
gal water to be applied in 300-500 gal water/acre, according to label; for
concentrate applications, use 80-100 gal water/acre, or lower if label allows.

+

Restricted entry interval (R.E.I.) is the
number of hours (unless otherwise noted) from treatment until the treated
area can be safely entered without protective clothing. Preharvest interval
(P.H.I.) is the number of days from treatment to harvest. In some cases the
REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.

*

Permit required from county agricultural commissioner for purchase or use.

1

Rotate chemicals with a different
mode-of-action Group number, and do not use products with the same
mode-of-action Group number more than twice per season to help prevent the
development of resistance. For example, the organophosphates have a Group
number of 1B; chemicals with a 1B Group number should be alternated with
chemicals that have a Group number other than 1B. Mode of
action Group numbers are assigned by IRAC (Insecticide Resistance
Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.